Today, there is demand for an apparatus which allows pictures, which are encoded as picture information for presentation on an electronic monitor, such as a CRT or LCD type providing a color display, to be recorded as visible pictures on printing papers and other recording media such as photographic film. Such a recording apparatus should enable a person to view the conditions of a picture on a monitor before actually recording it, and then preferably utilize the same monitor to produce an image for recording.
An electronic color image is generally constructed from a two dimensional array of elements called "pels" or "pixels" (for picture elements). These pels each contain the color and intensity information at a single resolution point in the original electronic image. Ideally, an electronic color display system can reconstruct an exact likeness of the original electronic image. In practice, electronic color display system limitations can cause the reconstructed image to fall short of the original electronic information.
One of these shortcomings has to do with the difference between the way pels are captured (e.g., by a television pickup) or constructed (e.g., by a computer), as coincident locations, and the way they are rendered on common electronic color monitor displays, as adjacent elements (usually dots or stripes) grouped in a triad. Each element of a triad produces one of three primary colors. It is only when an image rendered on the screen of such electronic color display is viewed from a sufficient distance that its color triads appear to merge and reform into pels with coincident colors.
Another shortcoming of usual color display copying practice is a loss of resolution in the copy compared to that available in both the source and the photosensitive medium, due to the lower resolution limits of available electronic color displays, typically in the range of 600 to 800 lines compared to well above 2000 lines readily available in photographic recording materials. For digitally created picture information sources the resolution is often limited only by memory size, which has increased rapidly with computer technology.
It is for the above reasons, among others, that prior art color hard copy recording apparatus using a color monitor for imaging have fallen into disfavor.
The spatial-color artifact and resolution limit problems may be readily and surely solved by sending a replica of the video image signal, as provided to the viewing display, to a separate hard copy recording apparatus as has been the case with prior art. However, a recording apparatus which uses an imaging source different from the viewing display tends to be complex and require frequent re-calibration to ensure a close match between the image as viewed on the electronic color display and that recorded on the hard copy.
So although the simplest, and in some instances most desirable, approach (and the method used by some early apparatus) is to directly record the image from the screen of an electronic color monitor display onto a photosensitive recording medium, such a recording will capture the pels as triads and will therefore suffer from both spatial-color artifacts described above and loss of resolution to the extent that the viewable resolution of the electronic color display falls short of the resolution capabilities of the picture information source and the recording medium.